Effect of combined x-ray and diethyl sulphate treatments on mutation frequencies in rice (Oryza sativa L.)

Dry seeds of uniform size of the rice variety T(N)1 were treated with DES alone and in combination with X-rays. The combined treatments affected more adversely the different growth metrics in the M₁ generation and increased the frequency of appearance of chlorophyll and other mutations affecting various morphological characteristics in the M₂ generation as compared to the treatment with DES or X-ray radiation alone. With respect to the spectrum of mutations induced by DES treatment, the frequency of chlorophyll mutations was noted to be relatively higher than that of other morphological mutations. The appearance of xantha mutations was noted to be the most frequent in the DES treatment in contrast to their rare appearance in irradiated material. The combined treatment had a considerable effect in altering the frequency and spectrum of morphological mutations as well as increasing the frequency of micromutations for grain yield and plant height.